NP119 transfer case fluid question.

[Eagle80]

Hello,
This morning I decided to change the transfer case fluid in my 1980 wagon. I read on here that regular old Dex III fluid was what to use to fill the case. However when I pulled the drain plug to drain the old fluid, I got gear oil coming out instead of old transmission fluid. No mistaking the smell, it was not motor oil, definitely gear oil. I went ahead and filled the case with Dex III anyway, My question is has driving it around with gear oil instead of transmission fluid caused any damage? The fluid coming out looked clear and honey colored and I've never had any issue with the T-case at all. Should I have filled it back up with gear oil since that's been working so far?
Thanks!

[mo.eagles]

If no parts rolled out with the oil and your not hearing any noise their is probably no damage .

[JayRamb]

If I'm not mistaken, the 1980's said to use 10W30 oil.

[Eagle80]

10W30 was indeed what the my 1980 service manual calls for. However I read here http://forums.amceaglesden.com/index.php?topic=42442.0 that it changed to Dex III some time in the mid-80s. So that's what I used. I was just surprised to have gear oil come out when I pulled the drain plug. No issues so far although it hasn't been but 10 miles or so.

[macdude443]

This film covers the 1980 119 and it's service procedures.  They mention what fluid to use.

https://www.youtube.com/watch?v=6Ee0mPldhm8

[carnuck]

If you lived in a cold climate, the gear oil can starve the bearings and drive chain up top until it warms up enough to move around and lube. Motor oil breaks down

[macdude443]

Sorry, it's in this film:  https://www.youtube.com/watch?v=k6cma28QvH0

Not saying it's right or wrong, just in 1980 the "only acceptable lubricant was 10w30".

[carnuck]

That was then. It was changed by 82/83 because people didn't service tcases often enough and non-synthetic motor oil breaks down

[macdude443]

That was then. It was changed by 82/83 because people didn't service tcases often enough and non-synthetic motor oil breaks down

That's certainly a change for the better then.

[rollguy]

I would suggest that you drain the T C again to get out most if not all the remaining gear oil.  I would then suggest you change it again in a couple thousand miles, or until the fluid still looks new after a few thousand miles. ATF is the recommended fluid for many manual transmissions and other units starting in the 80's.